The present invention relates to a multilayer suspension for supporting a flying head slider provided with a magnetic thin-film head element or an optical head element, to a head gimbal assembly (HGA) provided with the multilayer suspension, and to a manufacturing method of the HGA.
In a magnetic hard disk drive (HDD) unit, magnetic write head elements for writing magnetic information onto magnetic hard disks and magnetic read head elements for reading magnetic information from the magnetic hard disks are in general formed on magnetic head sliders flying in operation above the rotating magnetic disks. The sliders are supported at top end sections of suspensions of HGAs, respectively.
Recent ever-increasing demands for downsizing of the HDD unit and for increasing of data storage capacities and densities in the HDD unit advance further miniaturization and weight reduction of the magnetic head slider and further increasing rotational speed of the magnetic hard disk.
A suspension for supporting such miniaturized and light-weighted magnetic head slider needs not only to precisely control a load applied to the magnetic head slider by properly adjusting its stiffness or rate of spin but also to further improve its windage-resistance performance and its vibration performance.
The windage of the suspension caused by the side wind produced by high-speed rotation of the magnetic hard disk will greatly influence the attitude of the flying magnetic head slider. In order to decrease the windage, it is necessary to make the thickness of the suspension as small as possible. However, if the thickness is too small, since the rigidity of the suspension itself will fall, its vibration performance deteriorates.
There are two kinds of suspension provided with a possibility of solving these mutually contradictory problems.
One is a partial etching suspension. A load beam of this partial etching suspension is made from a relatively thick stainless steel plate with a thickness of 100 xcexcm, for example. Only a bending section or load adjusting section of the load beam is half-etched to reduce its stiffness. Thus, no excess load will be induce at the top end section of the load beam even if the bending section is bent to a considerable extent, and also the rigidity of the remaining section of the load beam can be ensured. This suspension is completed by fixing an independent flexure provided with lead conductors to thus configured load beam by laser welding.
The other one is a multipart suspension. A load beam of this multipart suspension is made from a relatively thick stainless steel plate to improve the windage-resistance performance and the vibration performance. The load beam and a base plate are coupled by a resilient hinge made from a relatively thin stainless steel plate. The hinge configures a bending section or load adjusting section of the load beam to adjust the stiffness. Fixing of the hinge with the load beam and the base plate is executed by laser welding. Then, the suspension is completed by fixing an independent flexure provided with lead conductors to the load beam by laser welding.
These partial etching suspension and multipart suspension have however following problems.
The partial etching suspension is fabricated by etching a part of the load beam to a desired depth so as to adjust its stiffness. Since the stiffness changes depending upon the remaining thickness of the etched part, if the etching condition varies, the obtained stiffness will change accordingly. Therefore, it is quite difficult to always fabricate the suspension with an optimum constant stiffness. When fabricating this partial etching suspension, it is necessary to assemble the independent flexure with the load beam by laser welding. Thus, the laser welding process is additionally needed. Also, since the alignment of the flexure with respect to the load beam is difficult to execute with high accuracy, a high precision suspension cannot be expected.
The multipart suspension can be always fabricated to have an optimum stiffness because the hinge determines its stiffness. However, additional laser welding processes for fixing the hinge to the base plate, for fixing the load beam to the hinge and for fixing the flexure to the load beam are needed. Also, since the alignments of the independent components such as the flexure, load beam, hinge and base plate are difficult to execute with high accuracy, a high precision suspension cannot be expected.
It is therefore an object of the present invention to provide a multilayer suspension, an HGA provided with the multilayer suspension, and a manufacturing method of the HGA, whereby the number of laser welding processes during fabrication of the suspension can be greatly reduced and the precision of the suspension can be extremely improved.
Another object of the present invention is to provide a multilayer suspension, an HGA provided with the multilayer suspension, and a manufacturing method of the HGA, whereby a windage-resistance performance and a vibration performance of the suspension can be improved while optimally keeping its stiffness or rate of spring.
According to the present invention, a multilayer suspension includes a resilient bending section formed by partially removing at least portions of layers of a five-layer structure which includes a first metal thin-plate layer a first resin layer laminated on the first metal thin-plate layer, a second metal thin-plate layer laminated on the first resin layer, a second resin layer laminated on the second metal thin-plate layer, and a conductive layer laminated on the second resin layer, a resilient gimbal section for mounting a head slider, formed by partially removing at least portions of layers of the five-layer structure, and a rigid section for coupling the bending section and the gimbal section, formed by partially removing at least portions of layers of the five-layer structure.
Also, according to the present invention an HGA includes thus formed multilayer suspension and a head slider mounted on the multilayer suspension and provided with at least one head element.
Because the multilayer suspension is fabricated by partially removing at least portions of layers of the five-layer structure without assembling individually separated parts, the number of mechanical connections or coupling of parts can be minimized. Therefore, the number of laser welding processes during fabrication of the suspension and the HGA can be greatly reduced and the precision of the suspension and the HGA can be extremely improved. Also, because it is possible to ensure the rigidity, a vibration performance of the suspension and the HGA can be improved. Furthermore, because the thickness can be reduced, a windage-resistance performance of the suspension and the HGA can be also improved. Of course, it is possible to precisely control the stiffness of the suspension.
It is preferred that, in the bending section, at least the first metal thin-plate layer is selectively removed. Because the first metal thin-plate layer is fully removed, the stiffness in this section can be precisely reduced to a desired value.
It is also preferred that, in the bending section, the first metal thin-plate layer and the first resin layer are selectively removed. Because the first resin layer is additionally and fully removed, the stiffness in this section can be further reduced.
It is preferred that, in the bending section, at least one via hole is formed. By forming the via hole or holes, the stiffness can be delicately adjusted and the weight of the suspension and the HGA can be reduced.
It is also preferred that, in the rigid section, at least the first metal thin-plate layer, the first resin layer and the second metal thin plate layer remain. Because the two metal layers and the resin layer between them remain, sufficient rigidity can be ensured.
Preferably, in the rigid section, at least one via hole is formed to reduce the weight of the suspension and the HGA.
It is preferred that, in the gimbal section, the first metal thin-plate layer and the first resin layer are selectively removed. Thus, the stiffness in this section can be greatly and precisely reduced.
It is preferred that, in the gimbal section, a gimbal via hole is formed in its center. In this case, preferably, the first metal thin-plate layer has a dimple passing through the gimbal via hole, for directly depressing a rear surface of the head slider to be mounted on the gimbal section.
It is further preferred that the conductive layer consists of patterned trace conductors and patterned connection pads. Because the trace conductors and the connection pads and also the insulation layer or the second resin layer under them are patterned from the single piece layers, no retrofitting process is necessary and no misalignment will occur. As a result, a high precision suspension can be expected.
It is preferred that the first and second metal thin-plate layers are formed by stainless steel thin plates, that the first and second resin layers are formed by polyimide resin layers, and/or that the conductive layer is formed by a copper layer.
According to the present invention, furthermore, a manufacturing method of an HGA includes a step of preparing a five-layer sheet which includes a first metal thin-plate layer, a first resin layer laminated on the first meal thin-plate layer, a second metal thin-plate layer laminated on the first resin layer, a second resin layer laminated on the second metal thin-plate layer, and a conductive layer laminated on the second resin layer, a step of forming a multilayer suspension by partially removing at least portions of layers of the five-layer sheet, the multilayer suspension including a resilient bending section, a resilient gimbal section for mounting a head slider and a rigid section for coupling the bending section and the gimbal section, and a step of fixing the head slider having at least one head element on the gimbal section of the multilayer suspension.
Because an HGA is assembled using a multilayer suspension body fabricated by partially removing at least portions of layers of the five-layer structure without assembling individually separated parts, the number of mechanical connections or couplings of parts can be minimized. Therefore, the number of laser welding processes during fabrication of the suspension and the HGA can be greatly reduced and the precision of the suspension and the HGA can be extremely improved. Also, because it is possible to ensure the rigidity, a vibration performance of the suspension and the HGA can be improved. Furthermore, since the thickness can be reduced, a windage-resistance performance of the suspension and the HGA can be also improved. Of course, it is possible to precisely control the stiffness of the suspension.
It is preferred that the forming step includes selectively etching and removing, in the bending section, at least the first meal thin-plate layer. Because the first metal thin-plate layer is fully removed by selective etching, the stiffness in this section can be precisely reduced to a desired value.
It is also preferred that the forming step includes selectively etching and removing, in the bending section, the first metal thin-plate layer and the first resin layer, respectively. Because the first resin layer is additionally and fully removed by selective etching, the stiffness in this section can be further reduced.
It is further preferred that the forming step includes forming, in the bending section, at least one via hole by etching. By forming the via hole or holes, the stiffness can be delicately adjusted and the weight of the suspension and the HGA can be reduced.
It is preferred that the forming step includes retaining, in the rigid section, at least, the first metal thin-plate layer, the first resin layer and the second metal thin-plate layer. Because the two metal layers and the resin layer between them remain, sufficient rigidity can be ensured.
In this case, it is preferred that, in the rigid section, the first resin layer has a thickness to form a damper structure.
It is also preferred that the forming step includes forming, in the rigid section, at least one via hole by etching to reduce the weight of the suspension and the HGA.
It is further preferred that the forming step includes selectively etching and removing, in the gimbal section, the first metal thin-plate layer and the first resin layer, respectively. Thus, the stiffness in this section can be greatly and precisely reduced.
It is preferred that the forming step includes forming, in the gimbal section, a gimbal via hole in the center by etching. In this case, preferably, the forming step includes forming a dimple passing through the gimbal via hole, for directly depressing a rear surface of the head slider by stamping the first metal thin-plate layer.
It is also preferred that the forming step includes forming trace conductors and connection pads by patterning the conductive layer. Because the trace conductors and the connection pads and also the insulation layer or the second resin layer under them are patterned from the single piece layers, no retrofitting process is necessary and no misalignment will occur. As a result, a high precision suspension can be expected.
It is preferred that the first and second metal thin-plate layers are formed by stainless steel thin plates, that the first and second resin layers are formed by polyimide resin layers, and/or that the conductive layer is formed by a copper layer.
It is also preferred that the forming step includes forming a multilayer suspension by partially removing at least part of layers of the five-layer sheet by selective etching.
Further objects and advantages of the present invention will be apparent from the following description of the preferred embodiments of the invention as illustrated in the accompanying drawings.